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duh? II

Well that was simple enough but now I have to ask is the only difference the upper pulleys and is it that simple? Putting an L upper on a HD and changing"stock tune" gives the HD 40 more h.p.? Seems like there has to be a catch here somewhere......... "Stock tune" needs what to be changed? Yeah, I AM this ignorant!

Well you can take two identical motors with the same amount of boost. One has a tune with say 14 degrees of timing and fatter A/F ratios and the other has 16 degrees of timing and leaner A/F ratios. The latter of the two will produce more HP. (Hope I got that Right).

Then you can factor in the parasitc loss that keeps the Harley from efficiently putting the HP down to the ground. Two peice steel drive shaft, heavier wheels/tire combo each, different rear end gears and overall weight of the vehicle.

I think that the lightnings wheel/tire combo weighs as much as our 20 inch wheel alone. The lightning also has a one peice aluminum drive shaft, and over all is lighter than the harley.

One of the experts will chime in here I am sure and give you some mathmatical computation to determine the parasitic loss in relation to rotational mass. LOl

Damn! That is good! So what should an old fart consider doing to his nice two HD's, if anything, other than just drive them and trade them in on SuperDuties? If I could kick up the performance a bit with low effort and expense, maybe it would make sense? I have a 2005 regular cab F250 being built this week with the newly improved 362 h.p. V-10 with 457 ft.lbs. of torque, a 4.30 posi, steps, best radio, 6 speed, etc. and going out the door for $23K including 6% sales tax and $3K rebate on employee discount (thnx to a bro-in-law who had been with Ford but was not when I got the two HD's but is again).

hey guys 1 more question id 6 is really 4, and 4 is really 2, then there is no point in putting on a 2lb'r is there since it wil put out 0?

not exactly, there is a ratio so its not an exact 2 lb less equation. a 2 lb will add some boost since its going to be a bigger diameter than the stock lower pulley since its the same size lower as a L's lower, but it wont add the same 2 lbs of boost it will on a L, but it has to add something since its a bigger pulley.

there was a chart somewhere's on here with the exact math figured out. ken800 on the boards years ago was great for doing the nitty gritty calculations for all that kind of stuff to find out the EXACT answers lol

I'd swap the lower to an 8 before swapping the upper to a L pulley. More belt wrap keeping the stock upper and going with a bigger lower = less belt slip.

I'd port the blower before adding even more boost though. I only had a 6 lb lower, stock upper, full ported intake setup (C&L, ported TB, smooth elbow, JLP ram air, S/C Spacer) and i'd see 18 lbs on the dyno, 16-17 on the track

What lenght belt?

I switched upper pulley to lightning pulley, but I have the 8lb pulley. I was running a 70 inch belt and from what I have researched I should continue to use the same belt. Help, it seems it would be too loose. GDY Goodyear/Gates Belt 70.00 inch Long Belt GDY-4080700